Silver halide photographic emulsions of enhanced light sensitivity



Patentecl May 11, 1948 111mm PA;

FQEFHCE ..;:2,441,440 .SILVER HALIDE PHOTOGRAPHIC I sroNs or ENHANCED LIGHT SENSITIVITY rllost'ell M; Nicholes, Highland Park, amil James r llar oldni'lfaylor, Parlin, N. J assignorsito E. I.

du Pont de Nemours & Company, Wilmington, Del;, a corporation ofiiDelaware N Drawing.

' This invention pertainstophotographic" emulsions "and more 'part-icularlyto- V eolloid 'silv-er halide emulsions swim need 'l'ight sens'iti'vity. Still more particularly pertains to gelatin-esilver halide'emul'sions f enhanced'lightesensii mas-sheen of photoerimentation; Thelma-is;still hiemyeempirical.

V Anirobjectmf:thisrinventionwds to provld new means; ZfOI" increasing the-light-sensittyity 1- laid-silver. halide (emulsion :Anotherembleet is to, i provide gelatinorsilyerrahalide emulsionsci enhanced light-sensitivity; --;util;izin,g available chemical compounds.- .earrelatedlnbjectgis toaprovide such emulsions using economical chemicals. A further object is to "increasei'the light-sensitivity of emulsionsby-ravsirnple and economical method. A stilliurther obj'ect; is to provide a method of preparing-gelatinwsilver-halide emulsions of increased light-sensitivity;-whichdoes not have a deleterious effect on the "spectral sensitivity of such emulsions". Stillf. other objects will be apparent-immetha of the invention. I H A i It has been discoveredthatcolloid-silver halide emulsions-lot increased; sensitivity-emanate made .by incorporatihg stlierewi-th althe condensation products of i'aliphatlczk; orJanamine. f-TheSe :condensation products may :be. incorporatedzwiththe'i emulsionigat, time during their preparation ,I'tbllt :1 l plieierably added after the initial preparation of the emulsions but before digestionhas been completed. In the casei ofge1atino=sili{er= halide emulsions it has been found that: erad'ditioni of the condensation products-of-aliphatici aldehydes with ammonia or aliphatic or. aromatic amines to such compositions,:results inkmulsions bf decidedly 7 Claims.

The .most practical com- Application January 25, 1945; Serial No. 574;;24

. J2 =Fres ly:prepare con ens p o ucts, for: Einstance, rsconfer less lightsensitivity :to an mu sio etha raeed;c nd sationpro c A egzgcambe accelerated byheating to ..an. elevated T he, color cf, .the; products likeise-rchange on ageing. Acetaldehyderammonia condensation products, for example. when freshly prepared are white crystals. On standing at room temperature for several weeks they change to a yellow. orgaa yellow redccolor. The lighter colored productsca'n be'rapidly changed by heating at an eievated'itemperature;below the melting point of the crystals for a short period. The darker colored jproductsgin general, give better results than thewhite colored products. Hence, the activity ofjzthe condensation; products can be correlated roughlyrwithjhein color...

The sensitizatiorrvconierred to the final colloid silver halideemulsions is. of the optical type and t mp ra u e.

gives; them 'a-n o'verall increase in speed, as disthe following description improved li'ghtesensitivltyl without. imparting any undesirable fog characteristics thereto.

It has been furtherdiscovered that the sensitivityi-ohtheremulsiopxdenends lapon tl e spee fic nature -ofetlaeacamiensatien{productsedescvibed aldehydesswithaa-mmmi? 40 ftijirrguishedffro'm" he"extra range-of spectral. sensitivity--conierred by-sensitizing dyes Theconden'sation products can-advantageously be-=used in conjunct-ierrwith spectral sensitizing dyes, 'eby modifying the n'ormal spectral-sensitivity F speed of emulsions.

"*Thereasons-Fthe aldehyde amn onia -'oraldehyde-amine complexes increase the sens-itivity -is not fully understood. It is due to the chemical nature of the--complexes-orcondensation products, becauisa theiuse of the individual components separately o t'fini-ira'dmixture with each other in a single emulsion produce no comparable sensitization. j 7

There are obyiously various ways of bringing the condensation productsinto operative contact with the silven salts ands-colloid binding agents. The condensation-productsmay beincorporated in the emulsion atpractically any stage in its manuiacture and can, even be associated thereiwithf'aftercoatin "to formflightsensitivef layers. usfthe'silye halide emulsionilayers"canibe impregnated .wijthan aqueousolution or a dilute methane l o ethanplisolutioniofthe condensation pridducts. jirrother rnanner consists in in corporating them"in-a*hydrophilicicolloid psolw tion, e. g., aqueous gelatin andpoatingtheadmixture onto-a-gelatin-si-lverhalide layer.

The folldwing examples'.further illustrate the invention. i'ihei partsare byweight.

dimple- 1 Gelatino silver iodobreniide iemulsions were prepared containing 0, 18275, and37.5'0 milligrams of an acetaldehyde ammonia-ccndensation product having a melting range of about 70 to 80 C. and being yellow-colored crystals, per 1.5 moles of silver halide. The emulsions were then given a first digestion, washed, given a second digestion, brought to their maximum light sensitivity and coated onto a suitable support. The following effects on relative speed were obtained. A

Mgs. Acetalde- Relahyde-ammonia tive Present Speed Example 2 Mgs. Propanal- Egg" ammonia speed 1 o 100 2 25 105 3 50 11a 4 75 129 s 112.5 137 o 150 157 Example 3 A photographic gelatin silver halide emulsion was panchromatized by the addition of a suitable .cyanine dye and brought to its maximum light sensitivity. This emulsion was split into four equal parts before coating and from 0 to 333.3 mg. of the acetaldehyde-ammonia condensation product described in Example 1 was added per 1.5 mols of silver halide. Evaluation of the coated emulsions showed the following characteristics.

Rela- Mgs. Acetaldehyde-ammonia ggg Example 4 To an orthochromatized photographic gelatin silver halide emulsion, containing 1.5 mols of silver halide, was added from 0 to 7.5 mg. ethylidine aniline (an acetaldehyde-aniline condensation product described in U. S. Patent 1,658,220) before the second digestion period. Efiects are tabulated below.

Rela- Mgs. Ethylldine five A lhne speed a crotonaldehyde-anlline condensation product Example 5 A photographic gelatin silver halide emulsion coated on a support was over-coated with layers containing an acetaldehyde-ammonia complex of the type given in Example 1 in concentrations equivalent to from 0 to'25 mg; per 1.5 mols of silver halide. The relative effects on the sensitivity of the emulsions are shown as follows:

Rela- Mgs. Acetaldehydra-ammonia g g Example 6 To photosensitive gelatin silver halide emulsions, each containing 1.5 mols of admixed silver bromide and silver iodide, was added from 0 to 15 mgs. of a crotonaldehyde ammonia condensation product, being a yellow, amorphous solid having a melting range of 43 to 70 C. The emulsions were held at 120 F. for 60 minutes, coated on a suitable support, and the speeds were later determined. The efiect on the speed of the emulsion is tabulated below.

Rela- Mgs. Crotonaldehyde ammonia gzg Example 7 Selected concentrations from 0 to 30 mgs. of

(a yellow-amber colored liquid which is described in U. S. Patents 1,417,970; 1,780,326 and 1,780,334) were added separately to gelatin silver halide emulsions containing 1.5 mols of silver salts to produce the following speed increases.

7 Rela- Mgs. Orotonaldehyde aniline ggg Example 8 An acetaldehyde p toluidine aniline (described in U. S. Patent 1,638,220) condensation product in amounts ranging from 0 to 12.5 mgs. was added to photographic emulsions each containing 1.5 mols of silver halide. The following results were obtained.

Mgs. Aceta1de- Relahyde-p-toluldlno tive aniline Speed Example 9 From 0 to 5 mgs. of n-butyraldehyde-n-butylamine condensation product (a translucent amber maria-4o teem-pine glatin emuls'ioris ea'eh co'ntfiini'rig 125 mole of silver halide produced the following effects.

Mgs. Butyral- Reladchydc. I tive butylamine "Specd AI -irplace of the specific aldehyde-amniotii for aldehyde amine.condensation'iproductsineseribed an? th i'above examples, thereimay be substituted One or more This is not a very stable configuration, however, and secondary reactions lead to condensation products which are more complex structures. To illustrate this aldehyde-ammonia, was prepared by passing ammonia gas into an ether solution of acetaldehyde at temperatures of -33 (3., 0 0,, and 20 C. The reaction products were separated and one portion of each was subjected to a heat treatment which consisted of holding for 48 hours at 65 to 70 C. When resulting products were tested photographically the following data were obtained.

Cone. mgs. Temperature of Heat Relative Preparation Treatment per 1 Speed Fog 1 This product was a white crystalline addition compound made from 1 mol of acetaldchyde and 1 mol of ammonia.

It will be noted that the products increase in activity with increased temperature of preparation. Products made and kept at very low temperatures, e. g., +33 C. show little if any activity. The products made at such low temperatures when heated, however, become active. The maximum activity of the products is obtained by heat treatments of less than 48 hours at 65 to 70 C.

mm tfiisiperiddmdfsigniflcanttiacraserin dc :ntity occursn. v

Many useful addehdarnfironimaqxirplremdro rwii imown anu avai labie compourrds. nmong The aldehyde=arfimoriia o'r iam ine fcompiexes may be used: m ce traction lth kfiwh 'sensi tiz'ers'" I as miyi tmoureayepnen insotnietythiosulfia'te, and adleali niml: hypo plrosphitea They may also be usedi ccni'unctiomwitn tos iiinni bitm a entsgemuisio stabiii-ze'rs ang. spec- 'tral sensitizing-"dyes 'such a yanine,- carbocy- *mer ocyamnepcyszine, eocyariiriej pseiidofiemicyamne and styi yl (idler formers and other emulsion constituents Amounts of 1 to 250 milligrams of the condensation products per mol of silver halide represents a practical range and 5 to 50 mg. per mol a preferred range. initial activity of the condensation product, amounts representing 5- to 10-fold increases, or more, over the maximum amounts described herein, can be employed in the present process.

Colloid binding agents other than gelatin may be used in the emulsions and emulsion layers. Collodion, agar-agar, albumin, polyglycuronic acid, hydrophilic cellulose derivatives and vinyl alcohol polymers and interpolymers and polyamides for instance can be substituted in whole or in part for the gelatin of the emulsions set forth in the above examples.

Simple and mixed silver halide emulsions, e. g., silver chloride, silver bromide, silver-chloride bromide, silver bromide iodide, silver chloride iodide, etc. are benefited by the addition of the novel aldehydic products described in this specification.

The invention has many advantages. It provides stable emulsions of enhanced light sensitivity. Substantial increases in emulsion speeds can be attained without any material increase in fog. The process is simple and does not require any new or additional equipment to the photographic manufacturer.

Aldehyde-ammonia or -amine addition products which apparently are first formed by the interaction of these componentsg'especially at low temperatures, can be added to the emulsions if desired in place of the condensation products. The addition products upon aging of the emulsions are converted to condensation products which exhibit the beneficial results described above. This conversion is accelerated by an increase in temperature.

As many widely difierent embodiments of this invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not to be limited'except as defined by the claims.

We claim:

1. A colloid silver halide emulsion containing from 1 to 250 milligrams per mol of silver halide of a condensation product of an aliphatic aldehyde with a base taken from the group consisting of ammonia and primary amines.

2.. A gelatino-silver halide emulsion containing from 1 to 250 milligrams per mol of silver halide of a condensation product of an aliphatic aldehyde with a base taken from the group consisting of ammonia and primary amines.

3. A colloid silver halide emulsion containing from 5 to 50 milligrams per mol of silver halide However, depending on the of a eondensationproduct or an aliph'atic aldehyde with a base taken from the group consisting ofammonia and primary amines.

4. A gelatino-silver halide emulsion containing from 5 to 50 milligrams per mol of silver halide of a condensation product of an aliphatic aldehyde with a base taken from the group consisting of ammoniaand primary amines.

5. A gelatino-silver halide emulsion containin .from 1 to 250 milligrams per mol of silver halide of a condensation product of a saturated aliphatic aldehyde of 1 to 4 carbon atoms with a primary aromatic amine. V

6. Agelatino-silver halide emulsion containing .from 5 to 50 milligrams per mol of silver halide of a condensation product of asaturated aliphatic aldehyde of 1 to 4 carbon atoms with a primary aromatic amine.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,139,774 Sheppard et a1 Dec. 13, 1938 2,154,895 Fricke et a1. Apr. 18, 1939 2,247,569 Brunken et al. July 1, 1941 Peterson Apr. 14, 1942 

